@mixin color-contrast($color) {
  $r: red($color);
  $g: green($color);
  $b: blue($color);

  $yiq: (($r * 299) + ($g * 587) + ($b * 114)) / 1000;

  @if ($yiq >= 150) {
    color: #111111;
  } @else {
    color: $white;
  }
}

@function tint-color($color, $level) {
  @return mix(white, $color, $level);
}

@function shade-color($color, $level) {
  @return mix(black, $color, $level);
}

@function strip-unit($number) {
  @if type-of($number) == 'number' and not unitless($number) {
    @return $number / ($number * 0 + 1);
  }

  @return $number;
}